Arcing or arc fault is an electrical discharge through a normally non-conductive gas, usually air. Such arcing can occur internally in low-voltage electrical distribution equipment between exposed conductors of different electrical potentials, such as adjacent busbars or a busbar and ground. When an arc jumps from one conductor to another across an air gap, it can stretch and bend to follow the path of least resistance across the air gap.
The hazards of unexpected and/or uncontrolled internal arcing are well known and include potential damage to equipment and harm to personnel in the operating environment caused by arc flash and arc blast, hereinafter referred to for simplicity as arc blast. Arc blasts in typical electrical distribution equipment can release large amounts of energy that can produce intense pressures, extremely hot gasses, vaporized metals/polymers, and other harmful byproducts.
Techniques for controlling arcing are known in the art, including passive and active arc control techniques. Active arc control techniques usually include some form of sensing and a switching mechanism to control the arc current. Concerns with active techniques may include higher cost, nuisance breaker trips, speed, and undetected system failures. Passive techniques may include containment and directed venting of the arc energy and gasses. Other passive arc control techniques may include structural reinforcements to better withstand the byproducts from the arc. Neither of the above passive methods limits the duration of the arcing event.
In addition, some passive internal arc management devices, such arc resistant switchgear and the like, use ventilation conduits and/or tubes to vent the arc byproducts. However, the hot gasses, vaporized metals/polymers, and other byproducts remain sufficiently hot even after leaving the tubes or conduits to remain conductive, potentially damaging other components. Additional costs in components and assembly labor must be expended to address these concerns.
Thus, a need exists for an improved way to control and limit the damage caused by arcs in electrical distribution equipment and particularly the damage caused by extremely hot byproducts resulting from such arcs.